core: addthis dependency and make file additions(moving from linux)
Merge branch 'imagex_poll' of github.com:emmairwin/imagex_installkit into addthis_socialmedia
Merge branch '7.x-dev' of github.com:imagex/imagex_installkit into addthis_socialmedia
Merge pull request #35 from emmairwin/addthis_socialmedia

CORE:  Addthis socialmedia fields (dependency and download for addthis), moving from linux